(ECF No. 881).

Defendants sharply disagree with Plaintiffs’ contentions. Defendants assert that Interrogatory No. 17 improvidently seeks “discovery on discovery” without demonstrating bad faith or unlawful withholding of documents, and that Plaintiffs’ motion is otherwise premature.

II. DISCUSSION

Federal Rule of Civil Procedure 26(b)(1) provides, in relevant part, “Parties may obtain discovery regarding any nonprivileged matter that is relevant to any party's claim or defense and proportional[4] to the needs of the case.” Here, the parties dispute whether Interrogatory No. 17 is “discovery on discovery” seeking to elicit information concerning Defendants’ efforts to respond to Plaintiffs’ other discovery requests, and, if so, whether compelling such follow-up discovery is justified in this instance.

*3 Discovery on discovery has been described broadly as “any discovery seeking information regarding a party's preservation, collection, and retention efforts.” Culliver v. BP Exploration & Prod., Inc., Case No. 3:21cv4942-MCR-HTC, 2022 WL 19568966, at *1 (N.D. Fla. Nov. 29, 2022). Some courts have held that such discovery is not relevant because it does not go to the merits of the claims or defenses in the suit, while other courts have permitted such discovery where there is evidence of a specific deficiency in the production. See id. at *1-2. Moreover, courts have applied varying standards when permitting such discovery. Compare, e.g., Culliver, 2022 WL 19568966, at *2 (requiring the requesting party to explain in sufficient factual detail how the document production was insufficient because of the methods used to preserve, collect, identify, process, or produce documents) with Alley v. MTD Prods., Inc., Case No. 3:17-cv-3, 2018 WL 4689112, at *2 (W.D. Pa. Sept. 28, 2018) (requiring a showing of bad faith or unlawful withholding of documents).

Defendants contend that discovery on discovery requires special justification and may only be obtained on a showing of bad faith or the unlawful withholding of documents, citing Alley, 2018 WL 4689112, at *2. See also Brand Energy & Infrastructure Servs., Inc. v. Irex Corp., Civ. Action No. 16-2499, 2018 WL 806341, at *2 (E.D. Pa. Feb. 9, 2018) (“Federal courts will not compel a party to disclose its discovery process as a result of the opponent's mere suspicion that the party's process has not produced adequate documents.” (internal quotation marks and citation omitted)). Plaintiffs, on the other hand, contend that Interrogatory No. 17 is not truly “discovery on discovery” because it does not ask for details regarding the specific steps Defendants’ vendors took to preserve and collect evidence, and because it does not seek to uncover whether Defendants acted in bad faith or unlawfully withheld documents. (ECF No. 903 at 3-4). Plaintiffs also contend that actual bad faith or unlawful withholding of documents need not be shown to compel answers to Interrogatory No. 17. (Id. at 4 (citing cases)).

Despite their respective arguments, the parties do not identify any controlling authority establishing the requisite standard to be applied here, nor has the Court discerned any such authority based upon its own research. The Court disagrees with Plaintiffs’ suggestion that Interrogatory No. 17 is not discovery on discovery because it undeniably seeks to elicit information on Defendants’ preservation, search, collection, and retention efforts. However, determining whether discovery on discovery is warranted at this juncture is not immediately evident. Indeed, courts generally resist permitting such discovery on discovery due to “the danger of extending the already costly and time[-]consuming discovery process ad infinitum.” Freedman v. Weatherford Int'l Ltd., No. 12 Civ. 2121 (LAK)(JCF), 2014 WL 4547039, at *2 (S.D.N.Y. Sept. 12, 2014) (citing Hubbard v. Potter, 247 F.R.D. 27, 29 (D.D.C. 2008) (“Speculation that there is more will not suffice, if the theoretical possibility that more documents exist sufficed to justify additional discovery, discovery would never end.”)). What is certain, however, is that “[c]ourts nationwide have come to some agreement about discovery on discovery, despite differences on the minutiae,” and “courts that have examined this question have recognized that discovery on discovery is the exception, not the norm, and have authorized or denied it after carefully considering the facts of a specific case.” LKQ Corp. v. Kia Motors America, Inc., Case No. 21 C 3166, 2023 WL 4365899, at *5-6 (N.D. Ill. July 6, 2023) (collecting cases that apply a variety of standards and concluding that those standards essentially require that “concrete evidence be presented to the court to support the requesting party's request for discovery on discovery”). While a few courts, such as Alley, have required a showing of bad faith or unlawful withholding of documents to justify compelling discovery on discovery, nothing in the text of the Federal Rules of Civil Procedure requires such a heightened and narrow standard, and this Court declines to impose such a standard here. Moreover, the Court finds the thorough reasoning and thoughtful conclusions set forth in LKQ Corporation to be persuasive, and thus similarly concludes that a party requesting discovery on discovery “bears the burden of producing specific and tangible evidence of a material failure of an opponent's obligation to conduct a reasonable inquiry in the discovery process.” 2023 WL 4365899, at *7.

*4 Plaintiffs contend, generally, that they “are still in the dark” about which search terms and custodial sources Defendants searched or omitted, while pointing to five specific areas of concern in support of their quest for broad discovery on discovery. (ECF No. 881 at 6). Even so, Plaintiffs’ motion seeks an order compelling Defendants to respond to all of Plaintiffs’ Second Set of Interrogatories, not just Interrogatory No. 17, even though Plaintiffs’ briefing focuses their arguments on Interrogatory No. 17 and these five areas of concern.[5] Even so, Interrogatory No. 17 itself seeks to elicit information well beyond the five areas specified by Plaintiffs and beyond the specific Defendants to whom Plaintiffs contend these respective areas pertain. Rather, Plaintiffs’ motion seeks to compel such discovery on discovery via Interrogatory No. 17 regarding Defendants’ answers to all prior interrogatories (though Plaintiffs do not identify which ones) for which they supplied documents pursuant to the document production option set forth in Federal Rule of Civil Procedure 33(d). Because Plaintiffs have not produced specific and tangible evidence to support their sweeping and generalized accusations that Defendants materially failed to conduct reasonable discovery inquiries to warrant wholesale discovery on discovery, what remains for determination are the five specific areas of concern that Plaintiffs identify for propounding Interrogatory No. 17 and the specific Defendants to whom they pertain. The Court addresses each in turn.

1. Code Words

Plaintiffs contend that when initially negotiating search terms with Defendants, Plaintiffs emphasized the importance of including “terms of art or internally used codes, labels, phrases, jargon or other terminology” that were used by Defendants’ custodians. (ECF No. 882, ¶¶ 3-4). At that time, Defendants identified no such code words, and therefore Plaintiffs contend that Defendants did not use any such code words in their search methodologies except for well-known acronyms such as “MDI” and “TDI” and those used for industry associations. (Id. ¶ 5). Compounding their suspicions, Plaintiffs discovered text messages upon reviewing documents produced by Defendant BASF Corporation in which BASF's “employees or persons communicating with them” referred to MDI and TDI price increase letters as “love letters” or “love notes.” (Id. ¶ 6). Two such messages were proffered in support of Plaintiffs’ motion. (ECF Nos. 882, 884-3, 884-4). Consequently, Plaintiffs seek to compel Defendants, not just BASF Corporation, to identify all search terms used along with all other discovery on discovery that would be responsive to Interrogatory No. 17.

In response, Defendant BASF Corporation notes that it provided Plaintiffs the list of its initial search terms as early as October 27, 2021, and that it was not aware of any other search terms “that would hit on unique responsive documents not otherwise covered by Plaintiffs’ proposed search terms list.” (ECF Nos. 901, ¶¶ 21-22, 26; 901-10). The BASF Defendants also helpfully clarify that the persons communicating with BASF's employees in these messages were BASF's own customers, including members of Plaintiffs’ class, and not purported co-conspirator Defendants. (ECF No. 901, ¶ 29). The BASF Defendants add that BASF Corporation's productions included documents containing the phrases “love letters” or “love notes,” having produced seven other documents containing these phrases, and they reviewed 140 documents hitting on those search terms that had not previously been produced and thereafter produced 21 additional documents. (Id. ¶¶ 28-29).

Based upon the record presently before the Court, it is evident that Plaintiffs have not satisfied their burden of producing specific and tangible evidence of a material failure of the BASF Defendants’ obligation to conduct a reasonable inquiry of code words. The record suggests otherwise, reflecting that the parties have undertaken significant efforts to confer and collaborate as required by the applicable Federal Rules of Civil Procedure and that those efforts fruitfully generated the production of additional responsive documents implicating the phrases “love letter” and “love note.” Moreover, there is no indication that other documents containing relevant euphemisms or coded phrasings exist. Plaintiffs’ insinuations to the contrary are speculative. Accordingly, Plaintiffs have not established a basis for compelling the BASF Defendants, nor any of the other Defendants, to answer extensive discovery on discovery regarding previously propounded interrogatories seeking to elicit coded messages between purported co-conspirators.

2. Text Messages

*5 Next, Plaintiffs contend that Defendant Dow's searches for and production of text messages and other non-email communications on various platforms (e.g., WhatsApp, WeChat, etc.) are deficient because custodians had forgotten their passwords, failed to turn off the auto-delete function on their devices, or messages otherwise were not preserved (ECF Nos. 882, ¶¶ 8-9; 882-5), suggesting that Defendants’ production efforts were lacking in reasonableness, transparency, and completeness.

In response, Defendant Dow contends that the parties’ conferral record confirms that Defendants have been exchanging information with Plaintiffs regarding unavailable ESI for years. Dow notes that it began discussing its preservation of custodians’ data as early as June 2020, and that it participated in multiple conferrals and exchanged extensive correspondence describing its preservation efforts. (ECF Nos. 882-5; 898, ¶ 32). For instance, on September 28, 2021, Dow informed Plaintiffs that mobile data for two of its custodians was not preserved because those custodians departed from Dow before its preservation obligations arose. (ECF No. 898, ¶ 34). Dow also informed Plaintiffs that it inadvertently did not collect mobile device data for four other custodians upon their departure from Dow. (Id.). Notably, at that time, Dow also provided Plaintiffs with detailed information regarding its legal hold procedures for departing employees. (Id.). On October 29, 2021, Dow informed Plaintiffs that despite its efforts, mobile device data was unavailable for six custodians. (Id. ¶ 35). Then, on May 13, 2022, Dow provided Plaintiffs with a detailed letter listing known issues with custodians’ missing mobile device data, stating, in part:

(ECF No. 882-5 at 4). A detailed description, inclusive of custodians’ names and circumstances, was also contained in Dow's letter to Plaintiffs. (Id. at 4-5).

Based upon this record, Plaintiffs have not produced specific and tangible evidence that Dow unreasonably failed to fulfil its preservation and production obligations pertaining to its custodians’ texts and other non-email communications. Moreover, Plaintiffs proffer no evidence in this regard pertaining to any of the other Defendants.[6] Indeed, the record evinces robust and transparent explanations for why Dow was unable to produce data from the devices of certain of its custodians. Discovery on discovery is simply not justified here.

3. Personal Email Accounts

*6 Plaintiffs contend that they have asked whether Defendants’ personnel used non-employer email accounts to conduct business (e.g., personal email accounts, spouses’ accounts, etc.), but that certain Defendants would neither confirm nor deny whether such sources of potentially relevant ESI exist. (ECF No. 882, ¶ 10). Plaintiffs further contend that Defendant WCA “finally conceded” the existence of such emails and agreed to search custodians’ personal email addresses when Plaintiffs discovered an email, produced by WCA, that had been sent by a WCA custodian from his personal email address to a BASF employee. (ECF Nos. 881 at 8; 882, ¶ 11). Plaintiffs point to a letter received from WCA's counsel, dated November 10, 2021, stating that certain WCA employees occasionally used personal email addresses to conduct MDI/TDI-related business and that WCA has collected and is searching those email accounts for responsive documents. (ECF Nos. 882, ¶ 11; 882-7). Finally, Plaintiffs contend that, despite WCA acknowledging its employees occasionally used personal email accounts to conduct MDI/TDI-related business, WCA still has not informed Plaintiffs which custodians’ personal accounts were searched or whether such accounts could not be searched or collected. (ECF No. 882, ¶ 11). Plaintiffs argue that discovery on discovery is, therefore, warranted.

In response, WCA contends that Plaintiffs were long-aware that WCA custodians had used non-WCA messaging platforms to conduct some MDI/TDI business and that WCA advised Plaintiffs as early as March 2021 that it would make inquiries regarding sources of potentially responsive material and would produce data derived from those sources, and that materials produced from those sources would be easily discernable as such (i.e., from AOL or Gmail accounts, etc.). (ECF Nos. 884-5; 899, ¶ 35). WCA served its Responses and Objections to Plaintiffs’ First Set of Interrogatories (ECF No. 669-3) in May 2021, stating that it was producing documents derived from message applications or other email accounts as reflected in the documents being produced in accord with Federal Rule of Civil Procedure 33(d). (ECF No. 899, ¶ 36). WCA points out that its November 10, 2021 letter merely repeated its earlier acknowledgment that it was searching for responsive documents in custodians’ non-work accounts. (Id. ¶ 37).

Again, based upon the record presently before the Court, Plaintiffs have not satisfied their burden of producing specific and tangible evidence that WCA (or any other Defendant) materially failed to fulfil its preservation and production obligations pertaining to its custodians’ communications using their personal accounts. In fact, the record demonstrates WCA's diligence and reasonableness when responding to Plaintiffs’ underlying interrogatories, that it was transparent about unpreserved data from a handful of specified custodians, and that any such deficiencies do not evince a material failure to fulfil its preservation and production obligations.

4. “Go Gets”

Plaintiffs express dissatisfaction with Defendants’ searches for, and production of, documents that are identifiable and producible without the use of search terms or other review methodologies. The parties refer to these discovery requests as “go-and-get” or “go gets.”[7] Plaintiffs represent that the parties agreed that such “go gets” would be produced before any resolution of disputes regarding search terms. (ECF No. 881 at 8) (referring to the parties’ Stipulated Order Regarding Discovery of Electronically Stored Information (“ESI”) (ECF No. 313 at 6).[8] According to Plaintiffs, some Defendants, such as Dow, specified which “go get” documents were being searched for, while other Defendants, such as WCA, were vague or circumspect, stating that “ ‘we will take reasonable steps to locate and produce documents responsive to the “go-get” requests, including to the extent such requests require collecting material beyond the scope of the custodial collections underway,’ ” and that it would “ ‘produce the documents we agreed to produce, subject of course to the proportionality standards of Rule 26(b)(1).’ ” (ECF Nos. 882, ¶ 12; 884-5). Plaintiffs contend that compelling responses to Interrogatory No. 17 would clarify which document sources were included or omitted from Defendants’ “go get” searches. (ECF No. 881).

*7 Defendants respond that, ahead of their respective TAR reviews, they each confirmed for Plaintiffs that they would search for documents on a “go get” basis and that some but not all Defendants additionally identified the discovery requests to which these “go get” searches pertained. (ECF Nos. 896-1, ¶¶ 51-54; 897, ¶¶ 45-51; 898, ¶¶ 45-51; 899, ¶¶ 39-41; 901, ¶¶ 44-46). Furthermore, Plaintiffs do not allege that certain specified documents are being withheld or that specified sources of responsive documents are being overlooked or disregarded. In fact, the only Defendant whom Plaintiffs specifically criticize in this regard is WCA, seemingly for not describing its “go get” searches with specificity. (ECF No. 882, ¶ 12). Yet, the record reflects that WCA and Plaintiffs engaged in numerous conferrals regarding “go get” searches, during which WCA indicated that “most of the documents responsive to the requests [Plaintiffs] have identified will be in the custodial files we are collecting.” (ECF No. 899, ¶ 40). Moreover, WCA asserts, without contradiction, that it produced thousands of additional documents on a “go get” basis prior to commencing its TAR review and that Plaintiffs have not raised any such concerns with the adequacy of those productions over the past two years. (Id. ¶ 41).

Based upon the record presently before the Court, it is evident that Plaintiffs have not satisfied their burden of producing specific and tangible evidence that WCA (or any other Defendant) materially failed to fulfill its preservation and production obligations with respect to “go gets.”

5. Privilege and TAR Challenges

As the final bases for justifying discovery-on-discovery, Plaintiffs point to their previous challenges to the adequacy of Defendants’ privilege logs and TAR-generated document productions.

First, Plaintiffs assert that their informal challenges to the purported over-inclusiveness of Defendants’ privilege logs prompted Defendants to produce, or reproduce with narrower redactions, “thousands” of documents, including ten documents containing force majeure announcements; though, as specifically relevant to the instant motion, merely two such force majeure documents were produced by Huntsman, two force majeure documents were produced by WCA, and three force majeure documents were produced by BASF.[9] (ECF No. 882, ¶ 15 & Exhibits 8-17 (ECF Nos. 882-9 to 882-18); 897, ¶ 53; 899, ¶ 43). While there appear to be no pending disputes concerning Defendants’ privilege logs, Plaintiffs contend that their earlier challenges prompted certain Defendants to supplement their productions and therefore demonstrates Defendants’ failure to fulfill their discovery obligations to warrant generalized discovery on discovery. Even so, Plaintiffs’ contention must be evaluated in the broader context of the parties’ conferrals (see, e.g., ECF Nos. 897, ¶¶ 54-61; 899, ¶¶ 42-44), and their comportment with the Court's Stipulated Order Regarding Discovery of Electronically Stored Information. (ECF No. 313). In doing so, it is readily apparent that Defendants have not materially failed to fulfill their discovery obligations in this regard.

Second, Plaintiffs contend that their three prior motions to compel concerning Defendants’ search terms and TAR methodologies yielded an additional 18,000 documents from WCA, some of which encompassed force majeure announcements, internal presentations discussing MDI supply and proposing MDI output reductions, and internal emails discussing MDI sales and describing future commercial strategy. (ECF Nos. 881 at 8-9; 882, ¶¶ 13-16 & Exhibits 8-17 (ECF Nos. 882-9 to 882-18)). Plaintiffs further contend that their persistent efforts to obtain these additional documents necessitates the need for propounding Interrogatory No. 17 and that the Court should compel Defendants to answer it. The Court disagrees.

As with Plaintiffs’ arguments concerning the privilege logs, the Court similarly notes that the broader context surrounding Plaintiffs’ three previous motions to compel, and the Special Master's and the Court's related rulings, do not support Plaintiffs’ seeming insinuation that Defendants were improvidently obstructing the discovery process by ending their TAR reviews when they did. (See ECF No. 881 at 9 (arguing that “Defendants have withheld key responsive documents until Plaintiffs insisted on completeness”)). Rather, a fulsome review of the record demonstrates otherwise.

*8 Plaintiffs filed their first Motion to Compel Defendants to Use Certain Search Terms and TAR Methodologies on March 25, 2021. (ECF No. 455).[10] After extensive briefing, expert reports, expert testimony, and oral argument, Special Master Hon. James C. Francis IV (Ret.) recommended denying this motion,[11] determining, inter alia, that Plaintiffs “failed to demonstrate that their proposed search terms are the only reasonable option.” (ECF No. 529 at 26 (In re Diisocyanates Antitrust Litigation, Misc. No. 18-1001, 2021 WL 4295729, at *13 (W. D. Pa. Aug. 23, 2021)) (“First R&R”)). Plaintiffs objected. The Court overruled Plaintiffs objections[12] and adopted the First R&R on September 21, 2021. (ECF No. 549). Defendants, for their part, did not object to the First R&R and instead unilaterally modified their TAR procedures to address concerns expressed by the Special Master and disclosed those modifications to Plaintiffs. (ECF Nos. 532; 532-6; 899, ¶ 14). In adopting the First R&R, the Court directed Defendants to proceed as they proposed and outlined a process for validating the completeness of their TAR searches, affording Plaintiffs an opportunity to seek judicial review if they disagreed with Defendants’ assessment as to when their searches were complete. (ECF No. 549).

In accordance with the Court's Order, Defendants performed extensive search term testing to identify terms that would capture sufficient responsive documents and determine whether using disputed search terms would improve the search efficacy. (ECF Nos. 604, ¶¶ 32-34; 606, ¶¶ 11-25; 607, ¶¶ 14-22; 608, ¶¶ 24-30; 609, ¶¶ 9-18). In doing so, the parties engaged in extensive conferrals, leading Defendants to add several search terms, including certain of Plaintiffs’ proposed terms without modification and adopting some of Plaintiffs’ proposed terms in modified formats. (ECF No. 584, ¶ 16). Unsatisfied, however, Plaintiffs continued pressing for a substantially broader set of search terms and search strings and sought a new hearing with the Special Master, prompting Defendants to move for a protective order permitting them to use their selected terms (ECF Nos. 582, 583), while Plaintiffs moved to compel Defendants to use Plaintiffs’ search terms (ECF Nos. 589, 592). These motions were referred to the Special Master. (ECF No. 596).

As with Plaintiffs’ first motion, the Special Master recommended that Plaintiffs’ second motion to compel also be denied and that Defendants’ motion for protective order be denied as moot. (ECF No. 611 (In re Diisocyanates Antitrust Litigation, Misc. No. 18-1001, 2022 WL 173678 (W.D. Pa. Jan. 7, 2022)) (“Second R&R”)). In doing so, however, the Special Master determined that the Court's prior Order adopting the First R&R foreclosed further adjudication of the search term dispute at that juncture but did not “immunize the [Defendants’] production from challenge at the end of the day,” and that Plaintiffs would have an opportunity to challenge both the search terms selected by Defendants and the point at which Defendants chose to halt the TAR process based on the validation information that Defendants had committed to providing. (Id. at *4). Neither Plaintiffs nor Defendants lodged objections,[13] and the Court adopted the Special Master's Second R&R in its entirety on January 19, 2022. (ECF No. 619 (In re Diisocyanates Antitrust Litigation, Misc. No. 18-1001, 2022 WL 170036 (W.D. Pa. Jan. 19, 2022))).

Thereafter, Defendants substantially completed their productions and provided Plaintiffs with information regarding the validation of their TAR methodologies and search terms. (ECF No. 798 at 5-7). Consistent with the Second R&R[14] and the Court's Order adopting it, WCA stopped its TAR review upon estimating that it had located 73.81% of the responsive documents and the responsiveness rate of the final batches was under 15%. (ECF No. 899, ¶ 22). Unsatisfied, on August 9, 2022, Plaintiffs filed their third motion to compel, disputing yet again the adequacy of Defendants’ search terms and challenging whether Defendants’ TAR searches were reasonably complete. (ECF No. 705).

*9 As with Plaintiffs’ first two search term-related motions, the Special Master recommended denying their third motion insofar as it challenged the adequacy of Defendants’ search terms. (ECF Nos. 798, 800 (In re Diisocyanates Antitrust Litigation, Misc. No. 18-1001, 2022 WL 17668470 (W.D. Pa. Oct. 19, 2022) (collectively, “Third R&R”)). However, the Special Master also recommended granting Plaintiffs’ motion insofar as it challenged the completeness of the TAR searches conducted by Defendants WCA, Huntsman,[15] and Covestro. (Id. at *11-14).

In formulating his recommendations in his Third R&R, the Special Master referenced his First and Second R&Rs, and then stated that the “time has come” to address Plaintiffs’ challenge to Defendants’ search terms, concluding that the search terms utilized by the Defendants “have not been demonstrated to be unreasonable,” and that these search terms “adequately captured the critical issues that [P]laintiffs have identified.” (Id. at *7, 11). As for Defendants’ cessation of their TAR review, the Special Master noted that Defendants followed their proposed procedures as directed by the Court, while also noting that neither their proposed process nor the Court's directive adopting it included “specific metrics for deciding when the review had been adequate.” (Id. at *11). The Special Master undertook detailed qualitative and quantitative analyses and concluded:

(Id. at *12). The Special Master then addressed Defendants’ argument that additional TAR review would impose a disproportionate burden on them, concluding that, “[o]n balance, then, the proportionality factors favor requiring WCA, Huntsman,[16] and Covestro to continue their TAR review.” (Id. at *13). Importantly, the Special Master supplied an additional recommendation for determining when enough is enough, stating, “To reduce the probability of further dispute and to provide the parties with a benchmark, I recommend that each review may presumptively be terminated when the last two batches reviewed contain no more than 10% responsive documents.” (Id. at *13).

Plaintiffs’ Objections and Notice of Supplemental Authority followed. (ECF Nos. 804, 819). Thereafter, Defendants filed a Response to Objections. (ECF No. 812).[17] WCA, along with the other Defendants, elected not to object to the Third R&R and instead voluntarily resumed the TAR review to comport with the Special Master's newly articulated recommendation that the TAR review should not end until the responsiveness rate was below 10%. (ECF No. 899, ¶ 22). Thereafter, WCA's extended TAR review achieved a responsiveness rate of 7.19% and yielded approximately 18,000 additional documents. (ECF Nos. 882, ¶ 14; 889, ¶ 23). Of these 18,000 documents, Plaintiffs identify one three-page email string to suggest Defendants (and not just WCA) failed to undertake reasonable inquiry in the discovery process that they contend warrants broad discovery on discovery now.

*10 Based upon this record, the Court disagrees with Plaintiffs’ contention that WCA's production of these additional documents and the motions practice leading to this production demonstrate WCA's material failure to conduct a reasonable search when responding to Plaintiffs’ discovery requests. First, while the parties are dutybound to take reasonable steps to identify and produce relevant documents, perfection is not required. (First R&R at *6 (citing cases)). Second, the parties’ briefings and declarations filed in conjunction with their prior motions and with the instant motion demonstrate substantial cooperation and transparency despite their evident imperfections. Third, Plaintiffs’ reliance on a handful of documents amidst millions derived from TAR methodologies in the context of this globally situated antitrust case is simply not material. Finally, existing discovery resolution mechanisms, both informal ones between parties and formal ones involving the Court, have been effective in assisting the parties to resolve their differences. This aspect of the current motion seems more a collateral attack on the Special Master's three R&Rs than a meaningful justification for discovery on discovery regarding Defendants’ TAR review, of which Plaintiffs already know a great deal.

III. CONCLUSION

As noted above, “discovery on discovery” should be the exception, not the norm. Mere speculation about missing evidence is insufficient to allow such discovery. Rather, the party requesting it bears the burden of producing specific and tangible evidence of a material failure of an opponent's obligation to conduct a reasonable inquiry in the discovery process. See LKQ Corp., 2023 WL 4365899, at *7. Here, amidst years of extensive and voluminous discovery responses involving countless custodians from around the globe and the production of millions of pages of documents, Plaintiffs identify a handful of relatively limited discovery imperfections, portray those imperfections out of context, and downplay or ignore the parties’ extensive meet and conferral record. In the Court's estimation, Defendants’ efforts to comply with their discovery obligations, while not perfect, have been diligent, reasonable, and transparent, at least regarding the matters presented in Plaintiffs’ motion. Such imperfections do not justify compelling broad and extensive discovery on discovery as to all Defendants and across all discoverable topics. Here, on the current record, such imperfections do not even justify discovery on discovery directed at a specific Defendant or for a specific topic. Accordingly, Plaintiffs’ motion shall be denied, but without prejudice. Today's decision does not foreclose the possibility that limited and targeted discovery on discovery may be proper if supported by a well-founded record. Even so, Court authorization should be sought via motion before a party will be allowed to propound such discovery on discovery, which nonetheless must be drawn narrowly. See id.

For the foregoing reasons, Plaintiffs’ Motion to Compel Defendants to Respond to Plaintiffs’ Second Set of Interrogatories is DENIED.

Accordingly, this 7th day of November 2023, upon consideration of Plaintiffs’ Motion to Compel Defendants to Respond to Plaintiffs’ Second Set of Interrogatories (ECF No. 880), IT IS HEREBY ORDERED that said Motion is DENIED without prejudice.

(ECF No. 313 at 6).